? Flat Cam
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Pro
Joined: Jun 2008
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? Flat Cam
Recently had a complete rebuild of my original 427/390 engine. Done by the guy who does engines for Nabers. Took it to two good mechanics and the builder as well. Everyone seems to think one of the lifters needed adjustment. Pulled the VC today and even with correct adjustment, the rockers still rattle. Even fully warmed up with the VC off, minimal oil coming off the rockers. Usually, running the car with the VC off creates one heckuva mess, but not here. Great oil pressure (60# at idle). Checked three of the lifters on the right, from where the noise was emanating...they look great. Any thoughts? thanx s
Melting Slicks
Joined: Oct 2004
Posts: 3,345
Likes: 87
From: Northern MN
St. Jude Donor '13-'14-'15-'16-'17
All 16 lobes wouldn't go flat at the same time so you should see oil on some of the rockers. From what you describe it could be a plugged passage or the rear cam bearing could be installed incorrectly. Just some thoughts.
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Team Owner
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From: Greenville, Indiana
You crank the rocker nut down until it stops clicking, then turn the nut 1/4-3/4 turn, the clicking has stopped and you call it good.
How can you do a "correct" adjustment if these conditions aren't met?
If all the rockers are oiling, lack of oil shouldn't cause valve clatter at idle speed. Maybe at higher rpm, not idle.
Check the noisy rocker for a crack in the ball seat and/or make sure it is hitting the valve tip squarely.
Le Mans Master
Joined: Feb 2008
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From: Folsom CA
It is also possible that one lifter never pumped up, if a lifter is stuck it will adjust like a solid lifer. The only cure for a stuck lifter is to pull it out and replace it. I have taken many apart that were stuck, sometimes you find minor manufacturing defects, sometimes you find debree that found its way into the lifter and sometimes you find nothing at all but replacement cures the issue. When you open a lifter up do it on clean white paper towels. The oil will drain right through the paper towel but any debree will be traped on the paper surface for you to examine. Any little spec of material will hang a lifter check vavle open or stick the piston in the lifter.
If the noise is still there afer adjusting the lifter and the lifter adjusts normally the noise may be Piston scuff in the block making your piston rock in the bore. A scuffed piston can sound a lot like a bad lifter. I hope in your case it is a lifter. Most of the time you can spot piston scuff with a bore camera, you will see scuff marks on the cylinder wall if the piston is all the way down in the cylinder. Pull your spark plug wire from the noisy cylinder and see if the noise changes. Good Luck.
If the noise is still there afer adjusting the lifter and the lifter adjusts normally the noise may be Piston scuff in the block making your piston rock in the bore. A scuffed piston can sound a lot like a bad lifter. I hope in your case it is a lifter. Most of the time you can spot piston scuff with a bore camera, you will see scuff marks on the cylinder wall if the piston is all the way down in the cylinder. Pull your spark plug wire from the noisy cylinder and see if the noise changes. Good Luck.
Last edited by Westlotorn; May 1, 2011 at 04:22 PM.
Team Owner
Joined: Mar 2003
Posts: 26,118
Likes: 1,874
From: Greenville, Indiana
It is also possible that one lifter never pumped up, if a lifter is stuck it will adjust like a solid lifer. The only cure for a stuck lifter is to pull it out and replace it. I have taken many apart that were stuck, sometimes you find minor manufacturing defects, sometimes you find debree that found its way into the lifter and sometimes you find nothing at all but replacement cures the issue. When you open a lifter up do it on clean white paper towels. The oil will drain right through the paper towel but any debree will be traped on the paper surface for you to examine. Any little spec of material will hang a lifter check vavle open or stick the piston in the lifter.
If the noise is still there afer adjusting the lifter and the lifter adjusts normally the noise may be Piston scuff in the block making your piston rock in the bore. A scuffed piston can sound a lot like a bad lifter. I hope in your case it is a lifter. Most of the time you can spot piston scuff with a bore camera, you will see scuff marks on the cylinder wall if the piston is all the way down in the cylinder. Pull your spark plug wire from the noisy cylinder and see if the noise changes. Good Luck.
If the noise is still there afer adjusting the lifter and the lifter adjusts normally the noise may be Piston scuff in the block making your piston rock in the bore. A scuffed piston can sound a lot like a bad lifter. I hope in your case it is a lifter. Most of the time you can spot piston scuff with a bore camera, you will see scuff marks on the cylinder wall if the piston is all the way down in the cylinder. Pull your spark plug wire from the noisy cylinder and see if the noise changes. Good Luck.
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Thanx for your help guys and sorry I didn't convey the facts very clearly. It is possible to tighten the rocker arms, and thus adjust the valves correctlly, but after a minture or so, the rattling and clatter begins again.
Under no circumstances does oil splatter from the pushrods as it should
(tho' it was a solid lifter car, when I tried to set the valves with the engine running in '70 LT-1, there was oil everywhere). I've decide to take the car to a professional mechanic tomorrow and get an opinion. I meant to mention that there's great oil pressure, but the car runs like crap from a dead start and can't maintain a constant, smooth idle for more than a minute or two.(The carb was done by Eric Jackson and the distributor by Bill Clupper, so I suspect an engine problem.) I've only heard piston slap once and it didn't sound like this. thanx again. s
Under no circumstances does oil splatter from the pushrods as it should
(tho' it was a solid lifter car, when I tried to set the valves with the engine running in '70 LT-1, there was oil everywhere). I've decide to take the car to a professional mechanic tomorrow and get an opinion. I meant to mention that there's great oil pressure, but the car runs like crap from a dead start and can't maintain a constant, smooth idle for more than a minute or two.(The carb was done by Eric Jackson and the distributor by Bill Clupper, so I suspect an engine problem.) I've only heard piston slap once and it didn't sound like this. thanx again. s
Le Mans Master
Joined: Feb 2008
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From: Folsom CA
Best of luck, sounds like a cam lobe going flat. I really hope I am wrong but that is what it sounds like to me. I have never adjusted big block rocker arms so the amount of oil squirting is better commented on by other members. Small blocks make a big mess with no valve cover while running.
Melting Slicks
Joined: Oct 2004
Posts: 3,345
Likes: 87
From: Northern MN
St. Jude Donor '13-'14-'15-'16-'17
Best of luck, sounds like a cam lobe going flat. I really hope I am wrong but that is what it sounds like to me. I have never adjusted big block rocker arms so the amount of oil squirting is better commented on by other members. Small blocks make a big mess with no valve cover while running.
BB's do the same. Messy when you leave the cover off with no other device to stop the oil from pumping in high volume. It gets all over.
By the way, one flat lobe will not cause the cam and lifters not to oil properly. According to his first post he is getting minimal oil to the lifters and rockers. When I purchased my car it had a miss in it that I couldn't get out. I tried everything. Finally pulled the valve covers and found one of the rockers moved very slightly. Knew right away that I had a flat lobe. The engine oiled like there was no tomorrow though. So I still think he has other problems and maybe a flat lobe.
Last edited by 66BlkBB; May 2, 2011 at 07:52 AM.
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Looking back at the first post, I realize that I made an error in the description. Too bad, 'cause it would have changed everything....sorry 'bout that. I only pulled the right VC, as it was the side with the noisy valve train. I never pulled the left.
The professional mechanic I took the car to this AM, did just that and it oils fine with no clatter on the left. Conclusion: most likely the the builder forgot the front galley plug on the right. Arggghhh. He doesn't want to pay the labor to pull the front engine accessories and timing chain cover, but I may yet prevail. I'll post the list when we get a look at that issue. Thanx s
The professional mechanic I took the car to this AM, did just that and it oils fine with no clatter on the left. Conclusion: most likely the the builder forgot the front galley plug on the right. Arggghhh. He doesn't want to pay the labor to pull the front engine accessories and timing chain cover, but I may yet prevail. I'll post the list when we get a look at that issue. Thanx s